Handle BOM in TOC files.
Added an option to forcefully update the addons.
Use a fail-safe installation procedure.

Put everything back in place if anything fails.
Do not use .addon-data.ini anymore.
Use externals from .pkgmeta to install needed libraries.
Squelch default error reporting when we do our own report.
Check the presence of svn and git prior to updating.
Bail out if no API key is found.
Do not whine on missing first argument.
Try to unpack the archive in a dry-run.
Refuse to overwrite git or svn working copies.
Bugfix on file iterations.
Safely handle filenames with non-alphanumeric characters.